Ukulib version strings connect a library release to a particular Minecraft target. This guide compares the late 1.x line with the newer 2.x line, explains major migration changes, and shows why upgrades should be planned as a compatible set.
Version numbers describe library changes
A Ukulib version such as 1.10.2+1.21.11 combines the library release with a Minecraft target. The suffix is important because two Ukulib releases can share similar features while supporting different game versions. Always read the complete version string.
The late 1.x line
The 1.10.x releases targeted Minecraft 1.21.11 and included compatibility fixes after breaking API changes. Earlier 1.9.x and 1.8.x releases targeted other 1.21 branches. These files are useful only when they match the dependent mod and loader in the selected instance.
What changed in Ukulib 2.0
Ukulib 2.0 arrived with Minecraft 26.1 support, added NeoForge compatibility, removed deprecated code, and changed the Maven artifact structure for developers. A major release can be a migration rather than a drop-in replacement, especially for mods compiled against the older API.
The 2.1.x maintenance line
The 2.1 releases updated the project for Minecraft 26.2 and included changes to platform-independent argument handling, button locations, and UI compatibility fixes. Players should still follow the dependent mod’s supported range instead of assuming every 2.1 file is compatible with every modern profile.
Plan upgrades as a set
Treat Minecraft, loader, Ukulib, and the dependent mods as one compatibility set. Create a copy of the instance, update only to releases targeting the same environment, launch, and inspect logs. Keep the old working profile until the upgraded set passes normal gameplay tests.